Fused silica with its outstanding chemical and thermal stability as well as excellent optical properties is widely used in the optics, microsensors and medical technologies. However, its robustness and brittleness pose challenges on processing it with conventional methods. In turn, ultrashort pulsed lasers with their unique properties offer the possibility for its gentle machining. Recent developments in laser and optics technology have led to the availability of frequency tripled ultrashort pulsed laser systems emitting in the ultraviolet spectral region with high pulse energy and average power, while exhibiting high beam quality and durability, motivating their application in micromachining of fused silica.
We report on ultraviolet ultrashort pulsed laser (UV) ablation of fused silica and compare the achievable machining results to the fundamental emission wavelength in the infrared (IR). The UV reveals a stable ablation efficiency at increasing fluences, while IR exhibits a decreasing trend. In addition, a significant improvement of surface quality is found by using UV laser in low and middle fluence regime as compared to IR. Specifically, a low surface roughness is found for UV with keeping a similar ablation efficiency of both wavelengths at middle fluence (about 10 J/cm²).
Identifying and taking advantage of the improved ablation results by using UV-ultrashort pulsed laser, we finally present exemplifying and sophisticated application examples of UV ultrashort pulsed laser ablation of fused silica.